1. Field of the Invention
The present invention relates to a process of producing a liquid-jet recording head for forming recording liquid droplets in an ink-jet recording system, a liquid-jet recording head produced by the process, and a recording apparatus equipped with the recording head.
2. Related Background Art
A liquid-jet recording head employed for an ink-jet recording system (liquid-jet recording system) has generally a fine discharge opening for ejecting a recording liquid (hereinafter referred to as an "orifice"), a liquid path, and an energy generation device for generating liquid ejection energy provided in a part of the liquid path. In a known process for producing such a liquid-jet recording head, a fine groove is formed on a plate of glass, metal or the like by a working method such as cutting and etching, and thereafter another suitable plate is bonded to cover the grooved plate.
However, conventional processes for the liquid-jet recording head production involve problems that the liquid path cannot readily be made uniform in liquid flow resistance owing to roughness of the liquid path wall worked by cutting or distortion of the liquid path by a difference in the etching ratio, tending to cause variation in the recording liquid discharging characteristics of the resulting liquid-jet recording head, and that breaks and cracks are liable to occur during cutting working, whereby the yield of production is low. The etching working includes many production steps to result in high production cost disadvantageously. Moreover, conventional processes for the recording head production have commonly disadvantages that the positional registration is difficult in bonding together the plate having a groove for the liquid path and the cover plate having a driving element such as a piezoelectric element and an electrothermal transducer for generating the liquid droplet discharge energy, which is not suitable for mass-production.
The liquid-jet recording head is usually brought into continual contact with the recording liquid in use conditions. Therefore, the materials for constructing the liquid-jet recording head should be resistant to the recording liquid not to cause deterioration in mechanical strength and not to impair the recording suitability of the recording liquid by releasing a detrimental component to the recording liquid. For conventional recording heads, the suitable material cannot necessarily be employed owing to restriction in the working method.
For solving the above problems in production of a liquid-jet recording head, a method is disclosed which comprises steps of providing a solid layer in a liquid path pattern on a substrate, applying a liquid path forming material to form a liquid path wall on the substrate having the above solid layer, and removing the solid layer from the substrate (JP-A-61-154947). This disclosed process enables production of a liquid-jet recording head with less variation of the discharge opening shape with high resistance to contamination by a foreign matter.
The ink (recording liquid) for ink-jet apparatus (liquid-jet recording apparatus) is desired to have higher water resistance to keep print quality against water depositing on the recording medium. For high water resistance of the ink, one method is use of a dye which is soluble only in an aqueous alkaline solution. However, when such a highly alkaline ink is used in the aforementioned liquid-jet recording head produced according to the above JP-A-61-154947, the ink tends to cause cracks of the liquid path forming material or separation thereof from the substrate.
The inventors of the present invention found that this phenomenon is caused by the after-effect of the dissolving liquid having been used in the solid layer removal step in the aforementioned head production process. Specifically, the dissolving liquid used in the solid layer removal step includes halogen-containing hydrocarbons, ketones, esters, aromatic hydrocarbons, ethers, alcohols, N-methylpyrrolidone, dimethylformamide, phenol, water, and strong alkali-containing water as described in the aforementioned JP-A-61-154947. From the above dissolving liquids, those are selected which is capable of removing quickly the solid layer without adverse effect such as swelling and dissolution of the resin material for forming the liquid path wall. However, few dissolution liquids satisfy all of the above requirements. The actually used dissolving liquids swell a little the resin material for formation of the liquid path wall. Therefore, the adhesiveness or the strength of the liquid path wall is locally impaired although the recording heads produced can be used without problem. The highly alkaline ink, which tends to swell the resin of the liquid path forming material of the liquid-jet recording head, is liable to cause separation of the liquid path wall from the substrate or to cause crack formation in the liquid path wall at the portion of low adhesiveness or low strength of the liquid path wall.